Lawn mower



12, 1941. G. w. DAVIS ET AL. 2,251,905

LAWN MOWER Filed Aug. 12, 1940 A TTORNEYJ Patented Aug. 12, 1941 LAWNMOVIE-R George W. Davis and Walter C. Davis, Richmond, Ind., assignorsto G. W. Davis Corporation, Richmond, Ind, a corporation of IndianaAppiicaticn August 12, 1940, Serial No. 352,188

2 Claims.

Lawn mowers of the type comprising a rotary cutter having acircumferentially spaced series of helical blades and an adjustablecoacting straight blade, have been manufactured in large quantities and,for many years, it has been commonly supposed that best grass cuttingresults could be obtained when the straight blade was so adjusted thatthe helical blades would lightly contact the straight blade. In thesemachines the straight cutter blade has generally been attached to acarrier pivotally mounted on bearings carried by the end plates of themachine to form a pivoted axis for the blade parallel with the axis ofthe rotary cutter, and generally associated with this carrier have beentwo adjustable temper screws mounted on each end plate and engaging thecarrier at two points, one on each side of the pivotal axis. The temperscrews have, of course, been so arranged as to be more or lessaccessible to the unskilled user who, when adjusting the same, was quitelikely to unevenly adjust them in such manner as to warp the carrier andits blade and thereby subject the end plates to such stresses as tocause them to crack.

We have discovered that the useful life of a lawn mower of this type maybe prolonged at its peak of cutting efliciency if the stationary bladeis at all times without internal stress and its active edge accuratelypositioned parallel with the axis of the rotary blade and uniformlyspaced from the cylinder of travel of the active edges of the helicalblades by an amount equal to the thickness of very thin paper.

The object of our invention, therefore, is to provide a mounting for thecarrier of the stationary blade that the active edge of its blade may bereadily so adjusted without subjecting the blade to warping stresses andthe end plate to injurious stresses.

The accompanying drawing illustrates an embodiment of our invention.

Fig. 1 is a vertical transverse section of a mower embodying ourinvention; and

Fig. 2 is a fragmentary section on line 22 of Fig. 1.

In the drawing I indicates an end plate of the mower, one of thetraction wheels and I2 the helical blades of the rotary cutter l3journalled in the end plates and connected to the traction wheels by anysuitable driving train.

Each end plate, is perforated at M, parallel with the axis of cutter l3,to receive a bolt l5 which, with its aligned companion, forms a pivotalaxis for the carrier I6 of the stationary blade H. The active edge ofblade ll is spaced to one side of the axes of bolts l5 and at the otherside of this axis and considerably more spaced therefrom, carrier I6 isprovided with a cylindrical lug I3 conveniently integral with thecarrier, as shown in Fig. 1.

Adjacent lug l8, end plate In is provided with a lug |9 having a finelythreaded perforation 20 at right angles to the axis of cutter l3.Threaded in perforation 2|! is an adjusting screw 2| which, at its lowerend, is provided with a pair of axially spaced collars 22, 22. A looknut 23, on the outer end of screw 2|, when brought into engagement withthe upper end of lug I9, serves to lock screw 2| in adjusted position.

The lug l8 and the adjacent faces of collars 22, 22 are accuratelymachined so that lug l8 may lie between the collars with a close runningfit Without appreciable play.

It will be noted that, with this construction, the active edge of thestationary blade may be accurately positioned either toward or from thecylinder of revolution of the edges of knives |2 by simultaneous equalturning of the screws 2|, 2| in the proper direction. Because of theaccurate fitting of lugs I8 between their associate collars 22, 22 theoperator does not need to exert any great force on screws 2| to firmlyposition the stationary blade, and because the threads of screws 2| arerelatively fine and lugs H; are considerably more spaced from bolts l5than is the active edge of blade ll a relatively considerable turning ofscrews 2| is required to cause a relatively small movement of the activeedge of blade I! toward or from the path of movement of the active edgesof blades It. The upper ends of screws 2| are readily accessible so thatthey may be readily simultaneously turned equally. It is, of course,possible to attain desired and proper adjustments by successive smallmovements of the screws 2| alternately without unduly stressing theparts.

We claim as our invention:

1. In a lawn mowe having a main body comprising connected side platesand a rotary cutter of the reel type journalled between said plates, acutter-bar carrier pivoted between the side plates on an axisparalleling the axis of the rotary cutter, a straight cutter-bar on saidcarrie positionable to coact with the reel type cutter, a lug carried bya side plate offset relative to the axis of said carrier and having athreaded perforation at right angles to the carrier axis, an adjustingscrew mounted in said perforation and having two axially-spaced rigidcollars, and a rigid lug carried by said. cutter-bar carrier and.

having opposed convex surfaces which engage rigid collars of theadjustment screw is substanand fit closely between said rigid collars.tially greater than the distance between the axis 2. A lawn mowerstructure of the character of the cutter-bar carrier and the active edgeof specified in the preceding claim, wherein the disthe straightcutter-bar.

tance between the axis of the cutter-bar carrier 5 GEORGE W. DAVIS.

and the contact between the carrier lug and the WALTER C. DAVIS.

